xpaconvert(7)

NAME
XPAConvert - Converting the XPA API to 2.0

SYNOPSIS
This document describes tips for converting from xpa 1.0 (Xt-based xpa) to xpa 2.0 (socket-based xpa).

DESCRIPTION
The following are tips for converting from xpa 1.0 (Xt-based xpa) to xpa 2.0 (socket-based xpa). The changes are straight-forward and almost can be done automatically (we used editor macros for most of the conversion).

•   The existence of the cpp XPA_VERSION directive to distinguish between 1.0 (where it is not defined) and 2.0 (where it is defined).

•   Remove the first widget argument from all send and receive server callbacks. Also change first 2 arguments from XtPointer to void *. For example:

    #ifdef XPA_VERSION static void XPAReceiveFile(client_data, call_data, paramlist, buf, len)
         void *client_data;
         void *call_data;
         char *paramlist;
         char *buf;
         int len; #else static void XPAReceiveFile(w, client_data, call_data, paramlist, buf, len)
         Widget w;
         XtPointer client_data;
         XtPointer call_data;
         char *paramlist;
         char *buf;
         int len; #endif

•   Server callbacks should be declared as returning int instead of void. They now should return 0 for no errors, -1 for error.

•   The mode flags have changed when defining XPA server callbacks. The old S flag (save buffer) is replaced by freebuf=false. The old E flag (empty buffer is OK) is no longer used (it was an artifact of the X implementation).

•   Change NewXPACommand() to XPAcmdNew(), with the new calling sequence:

      xpa = NewXPACommand(toplevel, NULL, prefix, NULL);

    is changed to:

      xpa = XPACmdNew(xclass, name);

•   Change the AddXPACommand() subroutine name to XPACmdAdd (with the same calling sequence):

      AddXPACommand(xpa, "file",
        "\tdisplay a new file\n\t\t  requires: filename",
        NULL, NULL, NULL, XPAReceiveFile, text, NULL);

    is changed to:

      XPACmdAdd(xpa, "file",
        "\tdisplay a new file\n\t\t  requires: filename",
        NULL, NULL, NULL, XPAReceiveFile, text, NULL);

•   The XPAXtAppInput() routine should be called just before XtAppMainLoop() to add xpa fds to the Xt event loop:

      /* add the xpas to the Xt loop */
      XPAXtAddInput(app, NULL);

      /* process events */
      XtAppMainLoop(app);

•   Change NewXPA() to XPANew() and call XPAXtAddInput() if the XtAppMainLoop routine already has been entered:

      xpa = NewXPA(saotng->xim->toplevel, prefix, xparoot,
                   "FITS data or image filename\n\t\t  options: file type",
                   XPASendData, new, NULL,
                   XPAReceiveData, new, "SE");

    is changed to:

      sprintf(tbuf, "%s.%s", prefix, xparoot);
      xpa = XPANew("SAOTNG", tbuf,
                   "FITS data or image filename\n\t\t  options: file type",
                   XPASendData, new, NULL,
                   XPAReceiveData, new, "SE");
      XPAXtAddInput(XtWidgetToApplicationContext(saotng->xim->toplevel), xpa);

•   Change XPAInternalReceiveCommand() to XPACmdInternalReceive() remove first argument in the calling sequence):

      XPAInternalReceiveCommand(im->saotng->xim->toplevel,
                                im->saotng, im->saotng->commands,
                                "zoom reset", NULL, 0);

    is changed to:

      XPACmdInternalReceive(im->saotng, im->saotng->commands,
                            "zoom reset", NULL, 0);

•   Change DestroyXPA to XPAFree:

      DestroyXPA(im->dataxpa);

    is changed to:

      XPAFree(im->dataxpa);

SEE ALSO
See xpa(n) for a list of XPA help pages